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How to set pulsating inlet boundary conditions with a very high frequency

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Old   April 28, 2009, 03:00
Default How to set pulsating inlet boundary conditions with a very high frequency
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Ton
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Hi,
I have a problem about how to set boundary conditions with a very high frequency.

I want to simulate a transient flow in a pipe. The inlet of pipe is mass flow rate (amplitude of sinusoidal flow) of 0.2 kg/s with frequecy 60Hz. The outlet of pipe is total pressure .

If the inlet of pipe is set mass flow rate, ANSYS CFX-Solver enforces inflow by erecting artificial walls on those faces where the flow attempts to exit the domain. The flow direction @inlet or outlet should change with time. So i set the inlet as velocity and outlet as openning. Is it OK?
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Old   April 28, 2009, 12:50
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Tristan Burton
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Ton,

You can turn off the artificial wall using Expert Parameters: Discretisation: Miscellaneous: build artificial wall: f. I've never tried it with a sinusoidal mass flow rate at my inlet, I've only done a sinusoidal total pressure at my inlet.

Tristan
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Old   May 3, 2009, 21:12
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Ton
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Hi Tristan,

Thanks for your details reply!

Ton
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Old   August 22, 2011, 14:13
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Hey Ton,

I am also trying to do a transient simulation with sinusoidal inlet flow. But i haven't got any idea on how i can change the boundary conditions to incorporate the sinusoidal inlet flow.
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Old   August 22, 2011, 21:39
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Glenn Horrocks
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This is easy to do with a CEL expression.
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Old   August 23, 2011, 08:35
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Hey ghorrocks,

Are there any tutorials on how to create the CEL expression for sinusoidal inlet mass flow rate ?

Thanks for your reply !
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Old   August 23, 2011, 19:05
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No, but it the CEL expession language is quite straight forward and once you have seen how the tutorials do it you will work it out. Have a look at the CFX tutorials.
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Old   August 24, 2011, 10:12
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Hey ghorrocks,

Thanks for your reply ! I am still having difficulty on understanding how i can incorporate CEL expression for Sinusoidal Inlet Flow Boundary Conditions ?

Thanks
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Old   August 25, 2011, 01:55
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Lance
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Quote:
Originally Posted by mysterious_man View Post
Hey ghorrocks,

Thanks for your reply ! I am still having difficulty on understanding how i can incorporate CEL expression for Sinusoidal Inlet Flow Boundary Conditions ?

Thanks
Have you tried the search function on the forum?
sine funtin
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Old   March 22, 2012, 11:44
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kamar
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Dear all,
I am using Ansys to simulate how sinusoidal pressure at the inlet of a tube propagates and arrives to the output.
I am going to record the pressure at both inlet and outlet on the same time.
Please can anyone tell me how i can do that.
many thanks
amoon
Quote:
Originally Posted by Ton View Post
Hi,
I have a problem about how to set boundary conditions with a very high frequency.

I want to simulate a transient flow in a pipe. The inlet of pipe is mass flow rate (amplitude of sinusoidal flow) of 0.2 kg/s with frequecy 60Hz. The outlet of pipe is total pressure .

If the inlet of pipe is set mass flow rate, ANSYS CFX-Solver enforces inflow by erecting artificial walls on those faces where the flow attempts to exit the domain. The flow direction @inlet or outlet should change with time. So i set the inlet as velocity and outlet as openning. Is it OK?
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Old   March 22, 2012, 17:57
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Glenn Horrocks
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Again, this is a routine CEL expression. Lance's link gives some further details. Do the tutorials and they demonstrate using CEL expressions.
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